A reserved word or character used to limit or expand your search. Frequently used operators include AND, OR, NOT, *, and ?. For example, steam AND generator finds all documents containing both terms (ignoring documents that contain only steam or generator but not both). Use quotation marks or parentheses to force a search of the operator itself: A search for steam "and" generator will find all documents containing any one or more of the three terms steam, generator, and and. To force a search of an entire phrase as a whole (and create any included operators as words), enclose it in quotation marks: "steam and generator" or parentheses (steam and generator). The alphabetical case of the operator does not matter. Alphabetical operators other than AND, OR, and NOT must be enclosed in angle brackets to be recognized (such as CONTAINS, MATCHES, NEAR, NEAR/x, STARTS, and ENDS).
Operators are special terms, such as AND and OR, that you can use to connect the words and phrases, focusing your search. For more information, see Operators.